Abstract: To understand the allelopathic potential of Cenchrus pauciflorus, the allelopathy of different concentrations （0,25%, 50% ,75%, 100% ） of seed aqueous extracts from Cenchrus pauciflorus on seed germination of Bromus inermis, Phleum pratense and Agropyron cristatum was assessed by bioassay. The results showed that the seed aqueous extracts from Cenchrus pauciflorus had effects on seed germination and seedling growth of the three gramineous grasses in different degrees. The seed aqueous extracts from Cenchrus pauciflorus had no significant effects on germination potential and germination index of Bromus inerrnis, but had significant effects on its ratio of root to sprout. The seed aqueous extracts from Cenchrus pauciflorus had no significant effects on germination rate, germination index and germination potential of Phleum pratense, but had significant effects on its ratio of root to sprout （P〈0.05）. The seed aqueous extracts from Cenchrus pauciflorus had significant effects on germination rate, germination index, germination potential and ratio of root to sprout of Agropyron cristatum （P〈0.05）; the germination rate of Agropyron cristatum seed in 100% seed aqueous extracts from Cenchrus paucifloru was 18.6%, which was decreased by 56.8% than that of control; the germination potential and germination index was 6.7% and 3.24, which was decreased by 39.3% and 8.94 than that of control, respectively.